Cardiovascular POCUS

Phased Array Plus Linear Dual Head Probe for Cardiovascular POCUS

A point-of-care ultrasound system at the bedside, probes racked at the top of the unit. A dual-head probe like the one described works with a portable base or streams to a phone. (Photo: Wikimedia Commons, CC BY-SA 4.0.)

A cardiovascular point-of-care study reads two depths on the same patient. The heart sits deep behind the ribs. The neck vessels and the leg veins run shallow under the skin. A dual-head probe puts a phased array at one end for the heart and a linear array at the other for the vessels. The clinician turns the probe over to move between them. One device covers the whole cardiovascular sweep, from a four-chamber view of the heart to a clot in a calf vein.

The two faces and their bands

The phased-array end runs at 1 to 5 megahertz through a small footprint. The narrow face fits between two ribs, the only window sound has into the chest. The low frequency reaches the far wall of the heart at fifteen to twenty centimetres. The linear end runs at 5 to 12 megahertz across a flat wide face. The high frequency draws fine detail in the first four or five centimetres, the depth a neck vessel or a forearm vein sits at.

Each end is a real, dedicated array, tuned for its own depth. The flip between them takes a turn of the wrist, the time it takes to reposition the probe on the skin.

What the phased end reads

Two 2D apical views from a focused cardiac echo, the windows the phased-array end captures. (Echocardiogram: Kjetil Lenes, Wikimedia Commons, CC BY-SA 3.0.)

The phased end opens the standard cardiac views. The apical four-chamber view comes from the point of the heart, all four chambers in one frame. The parasternal long-axis and short-axis views come from beside the sternum, reading the valves and the left ventricle. The subxiphoid view comes from below the breastbone, the angle that shows the sac around the heart. Each view answers a focused question.

The reads off these views run a focused cardiac exam. The reader grades how hard the left ventricle squeezes, a quick estimate of ejection fraction. A pericardial sac filling with fluid points to tamponade. If the right ventricle looks large against the left, a pulmonary embolism may be straining it. The inferior vena cava, read from the subxiphoid window, shows how full the circulation sits, its diameter and its collapse with a breath standing in for the filling pressure. Each is a number a cardiovascular decision turns on, caught in seconds.

Each view has its own landmark. The apical view comes from the point of maximum impulse, the probe marker turned to the patient’s left. The parasternal views come from the third or fourth rib space beside the sternum. The subxiphoid view comes from under the breastbone, the probe held nearly flat against the belly. The landmark decides the number. A foreshortened apical view flatters the squeeze. A tilted scan reads the vena cava at the wrong diameter. A reader works the view clean before trusting the figure off it.

What the linear end reads

The linear end works the vessels and the surface. The carotid artery in the neck shows its wall and any plaque narrowing the channel. The internal jugular vein beside it guides a central line, the needle watched into the vessel in real time.

The leg veins answer the question of a deep vein thrombosis, the two-point compression test pressing the femoral and the popliteal veins to see whether they squash flat or hold a clot. The forearm and the groin vessels guide an arterial line or a difficult cannula. The lung surface, read between the ribs with the linear end, shows the sliding of a healthy pleura and the B-lines of a wet lung.

These shallow reads round out the cardiovascular picture. A breathless patient with a strained right heart on the phased end gets a leg scan on the linear end, the clot in the calf explaining the heart. A patient in shock gets a heart read, a vena cava read, then a lung read, each from the probe already in the hand. The two ends together carry the whole question, the deep pump and the shallow plumbing, on one device.

The carotid read carries its own detail. The wall shows the intima-media thickness, an early mark of vascular disease measured in fractions of a millimetre. Any plaque is graded for how much it narrows the channel. The two-point compression for a clot presses the common femoral vein in the groin and the popliteal vein behind the knee, the two spots a clot tends to settle. A vein that squashes flat under the probe is clear. A vein that holds its shape holds a clot.

The cardiovascular POCUS protocols it serves

Several focused protocols lean on both ends in sequence, and the RUSH exam shows the design at full stretch. A patient crashes with no clear cause and the reader has minutes to name it. The phased end goes first to the subxiphoid window, where the heart shows whether it still squeezes hard and whether its sac has filled with the fluid that chokes a beat. The beam drops from there along the inferior vena cava, whose calibre and its travel with each breath read out how full the circulation sits. The reader sweeps the aorta on that same end, hunting the aneurysm that bleeds in silence. Then the probe flips. The linear end settles on the lung bases, where a lost sliding sign marks the air of a pneumothorax, and travels down the leg to press the femoral and the popliteal veins, where a vein that will not flatten holds the clot behind a pulmonary embolism. The whole survey crosses the chest, the belly, the legs without the reader ever setting the probe down. That unbroken sweep is the reason the dual head fits the work. A swap of probes at each step would spend the minutes the survey exists to save, and it would snap the thread of reasoning that ties a strained right heart to the clot found later in the calf. The other protocols ask less of the probe and the same of the design. The FOCUS cardiac exam stays on the phased end for the four windows, reading squeeze, sac, and the strain on the right side. Vascular access works the linear end, mapping the vessel and steering the needle into it under a live view. A clot study runs the two-point leg compression on the linear end. A lung sweep reads the B-line pattern that a wet lung throws up. Across all of them the flip keeps the study whole, carrying the reader from the deep cardiac question to the shallow vascular one in a turn of the wrist, on a cardiovascular bedside where the heart and the vessels fail on the same patient and the clock runs the whole time.

How the flip works

The two arrays sit back to back at opposite ends of one sealed housing. A mark or a small light shows which end is live. The device senses the orientation and loads the preset for the end now facing the patient, the cardiac preset for the phased end, the vascular preset for the linear end. Nothing unplugs between the two. There is no connector to corrode, no loose head to lose, no contact to wear with the swap. One sealed body wipes down as two faces on one wand. The reader keeps the whole cardiovascular range in one hand through the study.

Where the design serves

The dual head fits a clinician who reads the heart and the vessels on the same patient. A cardiologist running a clinic checks the heart on the phased end, then the carotid on the linear end, in one sitting. An emergency physician works a shock or a breathless call across the heart, the vena cava, the lungs, the legs.

A critical-care team sweeps a deteriorating patient through the cardiovascular system from one probe. A vascular service places lines on the linear end and checks the heart when a patient decompensates. For these the two ends answer the daily caseload, the deep cardiac view and the shallow vascular one held in a single device carried in a coat pocket.

On-board software measures the cardiovascular figures. An ejection fraction traces from the apical view. The inferior vena cava diameter, with its degree of collapse, comes off a frozen clip. On the linear image, the software gauges the carotid intima-media thickness. The reader checks each figure against the picture before it enters the record.

The scan streams to a phone over the wireless link for a remote read.

The fit follows the caseload. A practice that reads both the heart and the vessels on the same patients uses both ends through the day. A practice that reads only the heart, or only the vessels, can carry a single dedicated probe instead. The dual head suits the service where the two questions land on one patient, which on a cardiovascular round they often do.

Common questions about the dual-head cardiovascular probe

What is a phased array plus linear dual-head probe?

One sealed housing holds two arrays: a phased array at one end for the heart, a linear array at the other for the vessels. The clinician turns the probe over to move between the deep cardiac view and the shallow vascular one.

What frequency does each end run at?

The phased end runs at 1 to 5 megahertz to reach the heart between the ribs. The linear end runs at 5 to 12 megahertz for the neck vessels, the leg veins, and the lung surface.

Which cardiac views does the phased end give?

The apical four-chamber view, the parasternal long-axis and short-axis views, and the subxiphoid view. From these the reader grades the squeeze, checks the sac, sizes the right ventricle, and reads the inferior vena cava.

What does the linear end check?

The carotid artery, the internal jugular vein for line placement, the leg veins for a deep vein thrombosis by two-point compression, and the lung surface for sliding and B-lines.

Which POCUS protocols use the dual head?

The RUSH shock exam, the FOCUS cardiac exam, vascular access, deep vein thrombosis compression, and lung studies. RUSH uses both ends; FOCUS stays on the phased end.

How does the flip between ends work?

The two arrays sit back to back. The device senses which end is live and loads its preset. Nothing unplugs, so no connector or contact wears with the swap.

About the Author

Julien Mercier

Senior R&D Engineer · Medical Ultrasound Transducer Development

Senior R&D Engineer with an M.S. in Applied Physics and over 15 years of experience in medical ultrasound transducer development, specializing in the design verification and performance testing of high-frequency imaging transducers. Currently leading the development and verification of the company’s next-generation high-frequency linear-array transducer, responsible for imaging performance evaluation and reliability analysis in preclinical testing. Brings extensive hands-on experience in piezoelectric element tuning, beamforming parameter optimization, and system-level performance testing.