Transeptal puncture procedure

A medical method, comprising:

• inserting a distal end portion of a steerable sheath into a vascular system of a mammalian subject;
• advancing said sheath through the vascular system of the mammalian subject so that said distal end portion is located in a right atrium of the mammalian subject, a hollow needle with an ultrasound transducer at a distal end of said hollow needle being disposed in a lumen of said sheath;
• manipulating said steerable sheath, said hollow needle and said ultrasound transducer to position said ultrasound transducer in said right atrium within effective ultrasound transmission distance of a cardiac septum of the mammalian subject and so that a sharp distal tip of said hollow needle is spaced from a cardiac septum of the mammalian subject;
• thereafter actuating said ultrasound transducer to emit a pulsed ultrasonic pressure wave of predetermined duration;
• beginning a predetermined interval after termination of said pulsed ultrasonic pressure wave, monitoring incoming reflected pressure waves;
• calculating blood flow velocities from frequency shifts of the incoming reflected pressure waves;
• and
• operating an electro-acoustic transducer to generate an audible signal varying with Doppler frequency shift magnitude in accordance with direction of propagation and location at the fossa ovalis of said pulsed pressure wave from said ultrasound transducer into said left atrium.

A method for crossing a cardiac septum in a mammalian subject, comprising the steps of:

• providing a flow wire having a Doppler ultrasound transducer at a distal end thereof;
• inserting a distal end portion of said flow wire into a lumen of a hollow needle;
• advancing the hollow needle through a steerable sheath so that a distal end portion of the needle is located in a right atrium of the mammalian subject and so that the distal end portion of the needle is spaced from the cardiac septum without penetrating into the cardiac septum;
• manipulating the hollow needle and the flow wire to position said Doppler ultrasound transducer in said right atrium and facing towards the septum of the mammalian subject while that the distal end portion of the needle is spaced from the cardiac septum and does not penetrate into the cardiac septum;
• and
• thereafter actuating the Doppler transducer to transmit pulsed Doppler signals to scan blood flow velocity within a predetermined sample volume located transeptally in a left atrium of the mammalian subject.

An apparatus for enabling safe transeptal punctures, comprising:

• a hollow needle;
• a flow wire or guidewire disposed in a lumen of said hollow needle;
• an ultrasound transducer mounted to a distal end portion of said flow wire or guidewire;
• a waveform generator operatively connected to said ultrasound transducer and configured to energize said ultrasound transducer to produce a pulsed ultrasound pressure wave of predetermined duration;
• a signal receiver operatively connected to said ultrasound transducer;
• a signal processor operatively connected to said signal receiver and configured to detect magnitudes of Doppler frequency changes of ultrasonic waves reflected from one or more predetermined sample volumes at respective predetermined distances from said ultrasound transducer in a selected ultrasound-transmissive medium;
• and an electro-acoustic transducer operatively connected to said signal processor to generate an audible signal varying with Doppler magnitude as dependent on a direction of propagation of said pulsed ultrasound pressure wave in said selected ultrasound-transmissive medium.